Atkye ethers of s



Patented May 2, 1950 UNITED STATES PATENT OFFICE ALKYL ETHERS F- 3-HYDROXY- PHENOTHIAZINE David F. Houston, El Cerrito, Calif., assignor to the United States of America as represented by the Secretary of Agriculture N0 Drawing. Application August 23, 1949,

. Serial,No..111,964

(Granted under the .act, of March 3, 1883, as amended April 30, .1928; 370 O. G. 757) 8 Claims.

'1 This application is made under the act of March 3, 1883, as amended by the act of April 30, 1928, and the invention herein described, if patented in any country, may be manufactured and used;

by or for the Government of the United States of America for governmental purposes throughout the world without the payment to me of any royalty thereon. I

This invention relates to phenothiazine derivatives, particularly to alkyl ethers of B-hydroxyphenothiazine wherein the alkyl radicals contain at least 8 carbon atoms. These compounds correspond to the formula:

on s wherein R is an alkyl radical containing. at least 8 carbon atoms.

These compounds are useful as dyestuff intermediates, particularly for the preparation of oilsoluble dyestuffs by reacting them with an alkali metal sulphide, for example, sodium polysulphide. They are also useful as intermediates for the preparation of therapeutic compounds.

The alkyl ethers are prepared by fusing a p-alkoxydiphenylamine with sulphur in the presence of iodine as a catalyst. The reaction may be illustrated by the following equation, wherein R represents an alkyl radical containing at least 8 carbon atoms:

p-alkoxydiphenylemine 4- Has alkyl ether of S-hydroxyphenothiazine In accordance with this invention, therefore, the p-alkoxydiphenylamine is fused with sulphur in the presence of iodine as a catalyst. The amine and the sulphur are preferably employed in the ratio shown in the equations, namely,

- 8 carbon atoms. --wherein R. is octyl, nonyl, decyl, undecyl, dodecyl,

n UL

2 atoms of. sulphur to each mole of amine. The proportion of iodine is not criticaland generally it is employed in a proportion of about 0.5% to about 3.0%, based on the weight of the sulphur and amine reactants. The temperature of the fusion should be from about C. to about 200 0., preferably about l65-175 C. The time of reaction depends on the temperature used. In general, the reaction is continued until the evolution of H28 ceasesand preferably heating is continued; thereafter for a short time, say, 5 to 30 minutes.

The amine reactant may be any compound which corresponds to the formula:

wherein R is an alkyl group containing at least Thus the amines may be used tridecyl, ,tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, and so forth. The alkyl radical need not be a straight-chain (normal) radical but may be branched so that B may also be 2-methyl-heptyl, Z-ethyl hexyl, and so forth. It

EXAMPLE I Preparation of 3-n-octyloccyphenothiazine 5.95 grams (0.02 mol) of p-n-octyloxydiphenylamine was ground with 1.3 grams (0.04 atom) of sulphur and the mixture placed into a vessel together with 0.1 gram of iodine. The mixture was then heated at ISO- C. It was noted that after heating for 45 minutes the evolution of H28 had ceased and heating was discontinued. The fusion mass was allowed to cool then extracted with hexane until the extract was nearly colorless. The hexane extract was then concen trated by evaporation and allowed to cool whereupon the 3-n-octyloxyphenothiazine crystallized out of solution. The product had a melting point of 110.1 to 111.5 C. and was obtained in a yield of 80%. Analysis: C, 73.1%; H, 7.52%; N, 4.31% (calculated: C, 73.35%; H, 7.70%; N, 4.28%).

EXAMPLE II Preparation of n-doclecyl, and n-hexadecyl ethers of 3-hydroxyphenothiazine The process of Example I was repeated, substituting for the p-n-octyloxydiphenylamine, stoichiometrically equivalent amounts of p-ndodecyloxydiphenylamine, and p-n-hexadecyloxydiphenylamine, respectively. The products were obtained in yields of 80 to 84% as nearly white powders. The following results were also 3. Process in accordance with claim 1 wherein the amine reactant is p-dodecyloxydiphenylamine.

4. Process in accordance with claim 1 wherein the amine reactant is p-hexadecyloxydiphenylamine.

5. 3-octyloxyphenothiazine.

6. 3-dodecyloxyphenothiazine.

7. 3-hexadecyloxyphenothiazine.

8. A 3-alkyloxyphenothiazine wherein the alkyl obtained: radical contains at least 8 carbon atoms.

Analytical data, per cent Melting Alkyl group pgicnt, Carbon Hydrogen Nitrogen Found Oalcd. Found Oalcd. Found Galcd.

n-dodecyl. 101-103 75 1 75. 15 8.61 8. 67 3. 65 3. 65 n-hexadecyl 101. 5-103 76 4 76. 48 9. 9. 3. 21 3.19

DAVID F. HOUSTON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,024,477 Scott Dec. 17, 1935 2,123,928 Bosquet July 19, 1938 FOREIGN PATENTS Number Country Date 209,501 Switzerland July 16, 1940 209,502 Switzerland July 16, 1940 OTHER REFERENCES Pummerer et al.: Chem. Abstracts, vol. 7 (1913),

pp. 3337 and 3338. 

8. A 3-ALKYLOXYPHENOTHIAZINE WHEREIN THE ALKYL RADICAL CONTAINS AT LEAST 8 CARBON ATOMS. 